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There are two
introductory matters
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to be mentioned before we begin.
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The first is that
getting the level right
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for such a varied
audience is not easy.
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Some of you may well have
a postgraduate degree
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in molecular biology.
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But others may have had minimal
formal science education,
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and be facing jargon that is
much more difficult to deal
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with than the basic
and less technical
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content covered elsewhere.
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To the former, we look
forward to your contributions
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to the discussions, where
your perspectives should
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add to understanding
of the topics
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by those with a more
basic knowledge level.
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To the latter, the
two recommended
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introductory texts should help.
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Please see the course resources,
and please ask questions
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in the discussions.
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The participants in the MOOC
constitute a powerful learning
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community which can work
to the benefit of everyone.
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The second is that
we are now going
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to deal with the question of who.
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The content is focused
on DNA technology.
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And it does not deal with
personal identification
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from the pre-DNA era or from
other biometric measurements,
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such as fingerprints
or facial recognition,
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and only mentions earlier
forensic DNA technologies
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very briefly.
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Let's begin with
everyday identity.
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If you go to a concert,
or sporting event,
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or even a large shopping centre,
those around you will all be
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different-- male or
female; short or tall;
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blue eyed or brown eyed; black,
brown, red, or blonde hair,
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and in some cases
balding; of varied race;
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and with different
facial features--
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unless of course
we bump into twins,
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which is highly unlikely, as
only around 15 of every 1,000
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live births is of twins.
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If we change the
setting to a wedding,
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everyone will still
look different.
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But the range of characteristics
within each family
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will be smaller.
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The bride's family may
have several members
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who have red hair, while
the groom's family may
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have mainly dark brown hair.
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Pretty well everyone
today knows that we
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look the way we
do because that's
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the blueprint that our DNA laid
down to be followed as we grew
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from an embryo to an adult,
and that every blueprint,
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other than for identical
twins, is different.
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We also know that the elements
that make up the blueprint
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are inherited from our
parents, and that some,
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but not all of them, will
be shared by our siblings.
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The area of scientific knowledge
that encompasses our blueprint
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is called genetics.
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The field is still advancing,
but its modern roots
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can be traced to
the work of Gregor
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Mendel in the mid-19th century.
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Mendel observed that
certain traits in pea plants
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were passed from parent to
offspring in discrete units,
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functionally what we
would now call genes.
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Within a few
decades, it was shown
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that the units of inheritance
were located in structures
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in the cell nucleus
called chromosomes.
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But we had to wait another
50 years to find out
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the workings of the
mechanism of inheritance.
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This came with the
publication of Watson
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and Crick's famous
paper that showed
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that DNA in the chromosomes was
in the form of a double helix.
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It took about 10 more
years to elucidate
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how the information contained
in the sequence of bases
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was translated and
show that they defined
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the sequence of
amino acids required
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to synthesise a
specific protein.
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